Chip breaker



y 3, 1945- H. R. JOHNSON 2,375,367

' CHIP BREAKER Filed Dec. 9, 1942 r I!! FIG. Z. All 22 #42010 2. Jaw/x30. I N VEN TOR.

Patented May 8, 1945 I UNITED PATENT OFFICE" 2,375,367! A "CHIP BREAKER Harold Johnson, Mishawaka, Ind. Application December 9,1942, Serial No. 468,381 7 Claims. (Gist-42)v Ihis invention relates to a'chip breaker, and

more particularly to a device for breaking chips cut by the drill of a drill press from a work piece mounted in a work holder on the press.

Work holders commonlyhave 'drill bushings associated therewith and positioned above the work piece for'free rotative passage of a drill therethrough. If the lower end of the bushing is close to the top of thework piece,the elongated helical chips cut by a drill pass upwardly in the flutes of the drill and remain in said, drill flutes at the portion of the drill within the drill bushing. Thus the curled elongated chips are discharged at the top of the work holder, where theyare accessible for ready removal and do'not interfere greatly with the drilling operation or with the application and removal of successive work pieces to and from the work liolder. How-'- ever, in many cases, the work piece is of such size and shape that a substantial space j exists between the top of the work piece, which is clamped in the work holden'fand the lower end of the bushing. In such cases, the elongated curled or helical chip cut by the drill may not remain within the drill flute when it reaches the lower end of the drill bushing, so' that it strikes the end of said bushing andis deflected laterally outwardly thereby and winds around the drill. The deflected chip clogs or fills the space between the bushing and the work pieceQmakingv it difficult to remove and apply successive work pieces. Thus, if -chips clog the space between the bushing and the work holder clamp, .the operator is required to spend time in removing them. This entails a definite hazard because the edges'of the chip are usuallyverysharp, and hence the operator is likely to experience cuts on his hands. Clogging of the chipsin the manner; described also entails the disadvantage of interfering, with proper lubrication of the drill, so that .theusefu life of. a drill is measurably shortened. I p

The primaryobject of this invention is t provide a chip breakerby means of which the above described disadvantages maybe eliminated or overcome.

A further object is to provide a device by means of which a chip which is cut by a drill and-which projects from'the flutes of the drill maybe cut or broken into small pieces when it strikesthe lower end of the drill bushing.

A further objectis to provide a drill bushing having a lower or inner end provided with a plurality of circumferentially spaced radially positioned cutting teeth presenting abrupt. faces 55' form a circumferential series of equispaced sim- 1 and cutting edges to a chip fed helically into abutting engagement therewith.

A further object is to provide a drill bushing with a serrated lower-or inner end having a plurality of cutting edges.

Other objects will be apparent from the description and appended claims. a

In the drawing: I

Fig. 1 is a view in front elevation illustrating a work holder mounting a workpiece being drilled by a drill passing through a drill bushing and incorporating my 'chip breaker.

Fig. 2 is a view in side elevation with parts shown in section.

Fig. 3 is a fragmentary perspective view of a drill bushing having a chip-breaking serrated end.

and tiltably around stud 14.

Referring t0 the drawing, whichillustrates one embodiment of the invention, the numeral Ill designates the base plate of a work holder. upright plate portion II is carried by base ID. A block 12 is secured to base Ill and plate portion ll, said block including a forwardly projecting portion l3 provided with a vertical V-shaped recess in its front face. A horizontal screw threaded stud! is secured to plate ll adjacent to block l2 and projectsforwardly beyond the front face of portion I3 of block l2. An L-shaped clamp member havin goneleg lithereof bearing at its end against plate l2, and a leg I6, is provided with an opening in leg I 6 which fits slidably A retainer [1 is screw threadedon stud and is provided with laterally projecting'arms l8 by means of which the retainer may be rotated to tilt the clamp element about the end of leg l5 thereof as a fulcrum. A work piece l9, such as a forging, is seated in the recess in block l2, and is pressed upon and locked in operative position in said recess by leg "5 of the L-shaped clamp element.

A"forwardly extending horizontal plate 20 is detachably' secured by bolts 2|;to the upper end of plate I l in spaced relation above block I2. The

plate Z0 is constructed to cooperate with the work holderto accommodate the work piece 19 and the bore to be drilled therein. Thus the block is provided with a bore concentric with the axis drill bushing may be'of any desired construction l I and includes a cylindrical body portion 23 of a length to preferably project below the bottom face of plate 20. The lower projecting end of cylindrical portion 23 of the bushing is notched to ilar teeth 24. Teeth 24 preferably have one 1 7 abrupt face 25 and a gradually tapered face 26.

. Face 25 extends longitudinally of the drill bush- 3 ing and is preferably slightly undercut, i. e., lies in a plane inclined slightly relative to the axis of the bushing ,in the same direction that the face 26 inclines relative to the axis.

rection from the apex to the-base of said face as the direction ofrotation or the drill -21.- Con}- sequently as faces 26 are engaged by material This in-' clination of face 25 is preferably in the same di-- tion of long standing' namely deflection of the curled chip by the drill bushing, and winding thereof around the drill in a manner which clogs the space between the plate 20 and block I2.

'Such clogging action may involve interference with required free access to the work piece, in-

terference with drill lubrication, and necessity for the operator to .pull out the clogged chip by hand,

' which is timeconsumingand is also hazardous fed helically by said drill, they guide said material 1 intot he acute angled radial notches and against the abrupt faces 25 of the next tooth-amianiyv movement of the material along the abruptfaces 25 is man inward or rearward direction toward because of the flangenbfbutting. the hands on the sharp edges of the chip, 1 v It will be understood that the construction of the work holder and of the drill bushing and its mounting are illustrative only, and'are not in the base of the face-to insure retention of the material against sliding or displacement until the material is broken into chips. The edges of the, teeth, :and particularly :the edges at "the apieces of the teeth and at the inner sidev of faces I 25. are sharp and constitute -:cutting edges.

RDri'll 2i! has a free rotative .fitpwithin the :drill bushing. It will be understood :that'the drill 21 is mounted on a drill press, and that the work holder is mounted-upont'h'e work holdingplat form of said drill press.

During a drilling operation the chips cut'from the work piece.l9 assume helical shape and are :discharged by passing "upwardly through "the flutes of the'drill; As long as the chips aretpass ing upwardly through the hole bored in the work piece, they will be confined within the flutes.

Alscyif the spacing of-the lower or inner end of the drill bushing and the top of'the work piece I9 is small, the combination ofthe natural heli cal shape-.ofthe chip and the confiningaction of tended to be limiting, since the invention may I assume other .forms or embodiments within the scope .and spirit of the appended claims.

Iclaim:

E -A drill bushing having cylindrical body adapted to be mounted on. a stationary member and notched at .one ,end surface, each notch (extending longitudinally and being defined by converging end faces --o f whichs one is gradually tapered :andlthe other extends substantially parallelte the axis of; sai.d body- 5 .2. A (drill. bushing having adaptedto be mounted upon a stationary memberandhaving at least one. tooth in'its end-sur- .face, said tooth being definedin part by a longixtudinally extending faceflinterrupting said end 7 surface .andlying in a plane substantially parallel "totheaxisofithebody.

the wallofthe hole bored by the drill will serve .to retain thebhip-within the drill flute for passage 'through the bore of the :drill bushin and ,discharge .at the top of the plate .20. However.,

there are many cases where :a substantial space exists between the top of the' workpie'ce 4-9 and the inner end of the drill bushing because the size or'sha-pe of the work piece necessitates such 1- 1 spacing. I In-such cases, :t-he' aforementioned factors of helical chip shape and *c-hip zconfinement by bore walls may be ineffective to hold the chip I in the drillflute, andthe chip tends to slip "101 deflect out f thewdr-illflute toan extent which results .in;.conta:ct of the chip with the end "of the drill bushing, as iillustrated inedotted lines-at 30 i-n-sF-ig. '2. .When this occurs in r-the-instant de vice, the-:-chip is brought intoengagement with ,the abrupt face 25 and the sharp cutting edges of one of the teeth 24 at the lower or inner end of the drill bushing, and is broken or cutincident to the rotation :of the drill. The teeth 2-4 of the drill bushing are formed reverselyrelattve to the direction of rotation of thedrill, so. thatthe chips :are tedwagainstthe abrupt-tooth faces'fi the i rotating drill. The size rof the chip fragments which are cut or broken in this manner is smalL} and the. fragments are .free to fall, :as :upon the base plate l0 off-the work "holder. Consequer'rtly,

theymay-be removedieasil-y by means ofia brush or of an air blast when :an excessive quantity 3 thereof has accumulated-and they need not be} This overcomes a difficulty "in drill press opera-i :said tdrill rotates. a e

v a; 1n drill bushinglhaving .a cylindrical body adapted to be mounted on a stationary .member and notched at one end, said notches defining substan'tialy V shaped circumferentially spaced teeth, the faces of said teeth extending in acute angled relation to each jother'and each extenda ing in acute langled relation to a plane perpen dicular to thelaxis of said body.

4. Afdrillibushing having a cylindrical body adapted to be mountedfon a .stationary member and notchedat oneend tofform a circumferential seriesofspaced similar teeth, each of saidteeth I having an abrupt face and agradu'ally tapering "face and presentingsharp cuttingedges at its apex and 'attheinner edge of said ahruptface. 5; A drill bushingifo'r a rotating drill, compris 7 ine a'cylindrica-l body adaptedto be "mountedjon a stationary member and 'having a notched end surface providingwa circumferential series of, spaced teeth 'eachfof' said jteeth having an 'undercutfaee counter-rotationally disposed:relative to the rotative direction 'of-said drill and hav ing-cutting edges at their radial apices and at the inner edges of said undercut faces.

6, A (l-rill bushing having a tlibular body adapted to be mounted on a stationarymember for free rotation of adrill therein,'one endsurface of said body having a circumferential series of longitudinally projecting teeth therein, each presenting @an "abrupt fa'c'e in counter-rotational direction relative to the 'dire'ction o' f drill rotation. 7. A-drill bushing for a rotating drill, comprising a cylindrical body adapted to be mounted onwastationarymemberend having a longitudinal abutment interrupting one end surface thereof :and tacing in a :direction counter tdthat in which I HAROLD R.-;JQHNSON.-

afcylindrical body H 

